Salvia sclarea L. mediated green synthesis of gold nanoparticles (AuNPs) and evaluation of their antibacterial, anticandidal, and scolicidal properties

Gold nanoparticles (AuNPs) were biosynthesized using the aqueous extract of the aerial parts of Salvia sclarea L., and an environment-friendly and cost-effective method. These nanoparticles were then evaluated for antibacterial (4 standard bacterial strains), anti-candida (40 clinical isolates), and scolicidal effects. The UV-visible spectrophotometry revealed a maximum absorption peak at 548 nm for AuNPs. Field emission scanning electron microscopy (FE-SEM) showed that most particles had sizes in the 70–80 nm range. Also, energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were performed, revealing a crystal size of 11.2 nm, which was consistent with transmission electron microscopy (TEM), showing polygonal and spherical crystals between 20 and 50 nm. Dynamic light scattering (DLS) retrieved a mean diameter of 130.6 nm for these NPs. The reducing and stabilizing effects of the plant extract on AuNPs were confirmed by Fourier Transform Infrared Spectroscopy (FTIR). The AuNPs exhibited greater antimicrobial activity against Gram-positive bacteria, including Staphylococcus aureus and Bacillus cereus, than Gram-negative strains, such as Escherichia coli and Pseudomonas aeruginosa. Furthermore, these NPs showed noticeable activity against some Candida strains, such as Candida krusei and C. glabrata, but not against C. parapsilosis and C. albicans. The highest lethality (100%) of AuNPs against liver hydatid cyst protoscolices was obtained at the concentration of 320 µg/mL after 15 min treatment. Our results showed that the aqueous extract of S. sclarea L. could be a low-cost source for the biosynthesis of multifunctional AuNPs.